Self-calibration method for self-powered single ct current sensor

ABSTRACT

In an embodiment, a current sensor unit includes: a rectification module, to convert an AC current to a pulsed DC current; a conversion module containing an energy storage element, to store energy based upon the pulsed DC current during a charging mode and generate a power supply current; a switching module, bypassed by the conversion module during the charging mode, and bypassing the conversion module during an energy release mode; a current sensor module, to detect a pulsed DC current; a control module, to acquire electrical energy from the power supply current, determine operation in the charging mode or energy release mode, and acquire a first detection value provided by the current sensor module; and a self-calibration module, to generate a current flowing through the current sensor module in a self-calibration process, the control module calibrating the first detection value based upon a second detection value of the current generated.

PRIORITY STATEMENT

The present application hereby claims priority under 35 U.S.C. § 119 toChinese patent application number CN 202010037938.6 filed Jan. 14, 2020,the entire contents of each of which are hereby incorporated herein byreference.

FIELD

Embodiments of the invention generally relate to the field of electroniccomponents, in particular to a current sensor unit and a currentdetection circuit.

BACKGROUND

A current sensor is a detection apparatus, capable of sensinginformation of a current under test, and capable of converting detectedinformation according to a certain rule into an electrical signalconforming to the requirements of a given standard or into informationin another required form for output, in order to satisfy requirementsfor information transmission, processing, storage, display, recordingand control, etc.

At the same time as a current sensor is detecting a current, electroniccomponents of a signal conditioning part require a stable supply ofpower from a power source. In a conventional solution, an additionalpower source is generally used to supply power to this portion ofelectronic components. This additional power source might come from anindependent voltage source, or might come from an independent mutualinductor. However, this will make the circuit design complex, withcurrent sensor miniaturization being difficult and costs being high.

FIG. 1 is a schematic diagram of time division multiplexing of a mutualinductor in order to supply power to electronic components in a currentsensor in the prior art. In a solution typified by FIG. 1, the mutualinductor is used for supplying power for a period of time, and used forsampling for another period of time. However, this results in currentsensor sampling being performed intermittently, and thus a response isnot possible in the case of sudden current change events. For example,in the case of application in a power distribution system, it is notpossible to detect a short circuit current of a few milliseconds.

FIG. 2 is a schematic diagram of the continuous supply of power toelectronic components in a current sensor in the prior art. In asolution typified by FIG. 2, power is supplied continuously toelectronic components at a rear end of the current sensor, and a currentat the primary side of the mutual inductor is calculated by detecting acurrent outputted to the rear end by the mutual inductor. However, thisis a continuous supply of power, and a voltage-limiting device at thesecondary side must be able to tolerate a high power, so powerconsumption is high. Moreover, a secondary-side DC impedance includes anelectronic component equivalent impedance of a non-fixed value, and thishas an adverse effect on the linearity of sampling, and will also resultin low sampling precision.

SUMMARY

The embodiments of the present invention propose a current sensor unitand a current detection circuit.

At least one embodiment is directed to a current sensor unit,comprising:

a rectification module, configured to convert an AC current to a pulsedDC current;

a power source conversion module containing an energy storage element,connected to the rectification module and configured to store energy forthe energy storage element based upon the pulsed DC current duringoperation in a charging mode and to generate a power supply currentbased upon a voltage of the energy storage element;

a mode switching module, connected to the rectification module andconfigured to be bypassed by the power source conversion module duringoperation in the charging mode, and to bypass the power sourceconversion module during operation in an energy release mode;

a current sensor module, connected to the rectification module, thepower source conversion module and the mode switching module separatelyand configured to detect a pulsed DC current flowing back from the powersource conversion module or a pulsed DC current flowing back from themode switching module;

a control module, configured to acquire electrical energy from the powersupply current, determine that operation is in the charging mode or theenergy release mode based upon the voltage of the energy storageelement, and acquire a first detection value that is provided by thecurrent sensor module and relates to a pulsed DC current; and

a self-calibration module, configured to generate a predeterminedcurrent flowing through the current sensor module in a self-calibrationprocess;

wherein the current sensor module is further configured to detect thepredetermined current; and the control module is further configured tocalibrate the first detection value based upon a second detection valuethat is provided by the current sensor module and relates to thepredetermined current.

At least one embodiment is directed to a current detection circuit,comprising:

a current transformer, containing a primary-side circuit and asecondary-side circuit;

a current sensor unit, connected to an output terminal of thesecondary-side circuit, wherein the current sensor unit comprises: arectification module, configured to convert an AC current outputted bythe secondary-side circuit via the output terminal to a pulsed DCcurrent; a power source conversion module containing an energy storageelement, connected to the rectification module and configured to storeenergy for the energy storage element based upon the pulsed DC currentduring operation in a charging mode and to generate a power supplycurrent based upon a voltage of the energy storage element; a modeswitching module, connected to the rectification module and configuredto be bypassed by the power source conversion module during operation inthe charging mode, and to bypass the power source conversion moduleduring operation in an energy release mode; a current sensor module,connected to the rectification module, the power source conversionmodule and the mode switching module separately and configured to detecta pulsed DC current flowing back from the power source conversion moduleor a pulsed DC current flowing back from the mode switching module; acontrol module, configured to acquire electrical energy from a powersupply current, determine that operation is in the charging mode or theenergy release mode based upon the voltage of the energy storageelement, and acquire a first detection value that is provided by thecurrent sensor module and relates to a pulsed DC current; aself-calibration module, configured to generate a predetermined currentflowing through the current sensor module in a self-calibration process;wherein the current sensor module is further configured to detect thepredetermined current; and the control module is further configured tocalibrate the first detection value based upon a second detection valuethat is provided by the current sensor module and relates to thepredetermined current.

At least one embodiment is directed to a current sensor unit,comprising:

a rectification module, configured to convert an AC current to a pulsedDC current;

a power source conversion module containing an energy storage element,connected to the rectification module and configured to store energy forthe energy storage element based upon the pulsed DC current duringoperation in a charging mode and configured to generate a power supplycurrent based upon a voltage of the energy storage element;

a mode switching module, connected to the rectification module andconfigured to be bypassed by the power source conversion module duringoperation in the charging mode, and configured to bypass the powersource conversion module during operation in an energy release mode;

a current sensor module, connected to the rectification module, thepower source conversion module and the mode switching module,separately, and configured to detect a pulsed DC current flowing backfrom the power source conversion module or a pulsed DC current flowingback from the mode switching module;

a control module, configured to

-   -   acquire electrical energy from the power supply current,    -   determine that operation is in the charging mode or the energy        release mode based upon the voltage of the energy storage        element, and    -   acquire a first detection value provided by the current sensor        module and relating to a pulsed DC current;

a self-calibration module, configured to generate a current flowingthrough the current sensor module in a self-calibration process;

wherein the current sensor module is further configured to detect thecurrent generated; and

wherein the control module is further configured to calibrate the firstdetection value based upon a second detection value provided by thecurrent sensor module and relating to the current generated.

At least one embodiment is directed to a current detection circuit,comprising:

a current transformer, containing a primary-side circuit and asecondary-side circuit;

a current sensor unit, connected to an output terminal of thesecondary-side circuit, the current sensor unit including

-   -   a rectification module, configured to convert an AC current        outputted by the secondary-side circuit, via the output        terminal, to a pulsed DC current;    -   a power source conversion module containing an energy storage        element, connected to the rectification module and configured to        store energy for the energy storage element based upon the        pulsed DC current during operation in a charging mode and        configured to generate a power supply current based upon a        voltage of the energy storage element;    -   a mode switching module, connected to the rectification module        and configured to be bypassed by the power source conversion        module during operation in the charging mode, and configured to        bypass the power source conversion module during operation in an        energy release mode;    -   a current sensor module, connected to the rectification module,        the power source conversion module and the mode switching        module, separately, and configured to detect a pulsed DC current        flowing back from the power source conversion module or a pulsed        DC current flowing back from the mode switching module;    -   a control module, configured to        -   acquire electrical energy from a power supply current,        -   determine that operation is in the charging mode or the            energy release mode based upon the voltage of the energy            storage element, and        -   acquire a first detection value provided by the current            sensor module and relating to a pulsed DC current;    -   a self-calibration module, configured to generate a current        flowing through the current sensor module in a self-calibration        process;    -   wherein the current sensor module is further configured to        detect the current generated; and    -   wherein the control module is further configured to calibrate        the first detection value based upon a second detection value,        provided by the current sensor module and relating to the        current generated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of time division multiplexing of a mutualinductor in order to supply power to electronic components in a currentsensor in the prior art.

FIG. 2 is a schematic diagram of the continuous supply of power toelectronic components in a current sensor in the prior art.

FIG. 3 is a demonstrative structural diagram of the current sensor unitof an embodiment of the present invention.

FIG. 4 is a first demonstrative circuit diagram of the current sensorunit of an embodiment of the present invention.

FIG. 5 is a first demonstrative circuit diagram of the signalconditioning module of an embodiment of the present invention.

FIG. 6 is a second demonstrative circuit diagram of the signalconditioning module of an embodiment of the present invention.

FIG. 7 is a second demonstrative circuit diagram of the current sensorunit of an embodiment of the present invention.

FIG. 8 is a demonstrative structural diagram of the current sensor unitwith a self-calibration function according to an embodiment of thepresent invention.

FIG. 9 is a demonstrative circuit diagram of the current sensor unitwith a self-calibration function according to an embodiment of thepresent invention.

FIG. 10 is a demonstrative flow chart of the self-calibration process ofthe current sensor unit in FIG. 9.

FIG. 11 is a first demonstrative circuit diagram of the voltage controlcurrent source of an embodiment of the present invention.

FIG. 12 is a second demonstrative circuit diagram of the voltage controlcurrent source of an embodiment of the present invention.

KEY TO THE DRAWINGS

300 current sensor unit 301 rectification module 302 power sourceconversion module 303 mode switching module 304 current sensor module305 control module 306 signal conditioning module 307 output module 308self-calibration module 401 primary-side circuit of current transformer402 secondary-side circuit of current transformer 403 current loopduring operation in charging mode 404 current loop during operation inenergy release mode 900-916 steps

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

The drawings are to be regarded as being schematic representations andelements illustrated in the drawings are not necessarily shown to scale.Rather, the various elements are represented such that their functionand general purpose become apparent to a person skilled in the art. Anyconnection or coupling between functional blocks, devices, components,or other physical or functional units shown in the drawings or describedherein may also be implemented by an indirect connection or coupling. Acoupling between components may also be established over a wirelessconnection. Functional blocks may be implemented in hardware, firmware,software, or a combination thereof.

Various example embodiments will now be described more fully withreference to the accompanying drawings in which only some exampleembodiments are shown. Specific structural and functional detailsdisclosed herein are merely representative for purposes of describingexample embodiments. Example embodiments, however, may be embodied invarious different forms, and should not be construed as being limited toonly the illustrated embodiments. Rather, the illustrated embodimentsare provided as examples so that this disclosure will be thorough andcomplete, and will fully convey the concepts of this disclosure to thoseskilled in the art. Accordingly, known processes, elements, andtechniques, may not be described with respect to some exampleembodiments. Unless otherwise noted, like reference characters denotelike elements throughout the attached drawings and written description,and thus descriptions will not be repeated. The present invention,however, may be embodied in many alternate forms and should not beconstrued as limited to only the example embodiments set forth herein.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections, should not be limited by these terms. These terms areonly used to distinguish one element from another. For example, a firstelement could be termed a second element, and, similarly, a secondelement could be termed a first element, without departing from thescope of example embodiments of the present invention. As used herein,the term “and/or,” includes any and all combinations of one or more ofthe associated listed items. The phrase “at least one of” has the samemeaning as “and/or”.

Spatially relative terms, such as “beneath,” “below,” “lower,” “under,”“above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. For example, if the device inthe figures is turned over, elements described as “below,” “beneath,” or“under,” other elements or features would then be oriented “above” theother elements or features. Thus, the example terms “below” and “under”may encompass both an orientation of above and below. The device may beotherwise oriented (rotated 90 degrees or at other orientations) and thespatially relative descriptors used herein interpreted accordingly. Inaddition, when an element is referred to as being “between” twoelements, the element may be the only element between the two elements,or one or more other intervening elements may be present.

Spatial and functional relationships between elements (for example,between modules) are described using various terms, including“connected,” “engaged,” “interfaced,” and “coupled.” Unless explicitlydescribed as being “direct,” when a relationship between first andsecond elements is described in the above disclosure, that relationshipencompasses a direct relationship where no other intervening elementsare present between the first and second elements, and also an indirectrelationship where one or more intervening elements are present (eitherspatially or functionally) between the first and second elements. Incontrast, when an element is referred to as being “directly” connected,engaged, interfaced, or coupled to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between,” versus “directly between,” “adjacent,” versus“directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments of the invention. As used herein, the singular forms “a,”“an,” and “the,” are intended to include the plural forms as well,unless the context clearly indicates otherwise. As used herein, theterms “and/or” and “at least one of” include any and all combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “comprises,” “comprising,” “includes,” and/or“including,” when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist. Also, the term “example” is intended to refer to an example orillustration.

When an element is referred to as being “on,” “connected to,” “coupledto,” or “adjacent to,” another element, the element may be directly on,connected to, coupled to, or adjacent to, the other element, or one ormore other intervening elements may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to,”“directly coupled to,” or “immediately adjacent to,” another elementthere are no intervening elements present.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, e.g., those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Before discussing example embodiments in more detail, it is noted thatsome example embodiments may be described with reference to acts andsymbolic representations of operations (e.g., in the form of flowcharts, flow diagrams, data flow diagrams, structure diagrams, blockdiagrams, etc.) that may be implemented in conjunction with units and/ordevices discussed in more detail below. Although discussed in aparticularly manner, a function or operation specified in a specificblock may be performed differently from the flow specified in aflowchart, flow diagram, etc. For example, functions or operationsillustrated as being performed serially in two consecutive blocks mayactually be performed simultaneously, or in some cases be performed inreverse order. Although the flowcharts describe the operations assequential processes, many of the operations may be performed inparallel, concurrently or simultaneously. In addition, the order ofoperations may be re-arranged. The processes may be terminated whentheir operations are completed, but may also have additional steps notincluded in the figure. The processes may correspond to methods,functions, procedures, subroutines, subprograms, etc.

Specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments of thepresent invention. This invention may, however, be embodied in manyalternate forms and should not be construed as limited to only theembodiments set forth herein.

Units and/or devices according to one or more example embodiments may beimplemented using hardware, software, and/or a combination thereof. Forexample, hardware devices may be implemented using processing circuitrysuch as, but not limited to, a processor, Central Processing Unit (CPU),a controller, an arithmetic logic unit (ALU), a digital signalprocessor, a microcomputer, a field programmable gate array (FPGA), aSystem-on-Chip (SoC), a programmable logic unit, a microprocessor, orany other device capable of responding to and executing instructions ina defined manner. Portions of the example embodiments and correspondingdetailed description may be presented in terms of software, oralgorithms and symbolic representations of operation on data bits withina computer memory. These descriptions and representations are the onesby which those of ordinary skill in the art effectively convey thesubstance of their work to others of ordinary skill in the art. Analgorithm, as the term is used here, and as it is used generally, isconceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of optical, electrical, or magnetic signals capable of beingstored, transferred, combined, compared, and otherwise manipulated. Ithas proven convenient at times, principally for reasons of common usage,to refer to these signals as bits, values, elements, symbols,characters, terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, or as is apparent from the discussion,terms such as “processing” or “computing” or “calculating” or“determining” of “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computingdevice/hardware, that manipulates and transforms data represented asphysical, electronic quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

In this application, including the definitions below, the term ‘module’or the term ‘controller’ may be replaced with the term ‘circuit.’ Theterm ‘module’ may refer to, be part of, or include processor hardware(shared, dedicated, or group) that executes code and memory hardware(shared, dedicated, or group) that stores code executed by the processorhardware.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

Software may include a computer program, program code, instructions, orsome combination thereof, for independently or collectively instructingor configuring a hardware device to operate as desired. The computerprogram and/or program code may include program or computer-readableinstructions, software components, software modules, data files, datastructures, and/or the like, capable of being implemented by one or morehardware devices, such as one or more of the hardware devices mentionedabove. Examples of program code include both machine code produced by acompiler and higher level program code that is executed using aninterpreter.

For example, when a hardware device is a computer processing device(e.g., a processor, Central Processing Unit (CPU), a controller, anarithmetic logic unit (ALU), a digital signal processor, amicrocomputer, a microprocessor, etc.), the computer processing devicemay be configured to carry out program code by performing arithmetical,logical, and input/output operations, according to the program code.Once the program code is loaded into a computer processing device, thecomputer processing device may be programmed to perform the programcode, thereby transforming the computer processing device into a specialpurpose computer processing device. In a more specific example, when theprogram code is loaded into a processor, the processor becomesprogrammed to perform the program code and operations correspondingthereto, thereby transforming the processor into a special purposeprocessor.

Software and/or data may be embodied permanently or temporarily in anytype of machine, component, physical or virtual equipment, or computerstorage medium or device, capable of providing instructions or data to,or being interpreted by, a hardware device. The software also may bedistributed over network coupled computer systems so that the softwareis stored and executed in a distributed fashion. In particular, forexample, software and data may be stored by one or more computerreadable recording mediums, including the tangible or non-transitorycomputer-readable storage media discussed herein.

Even further, any of the disclosed methods may be embodied in the formof a program or software. The program or software may be stored on anon-transitory computer readable medium and is adapted to perform anyone of the aforementioned methods when run on a computer device (adevice including a processor). Thus, the non-transitory, tangiblecomputer readable medium, is adapted to store information and is adaptedto interact with a data processing facility or computer device toexecute the program of any of the above mentioned embodiments and/or toperform the method of any of the above mentioned embodiments.

Example embodiments may be described with reference to acts and symbolicrepresentations of operations (e.g., in the form of flow charts, flowdiagrams, data flow diagrams, structure diagrams, block diagrams, etc.)that may be implemented in conjunction with units and/or devicesdiscussed in more detail below. Although discussed in a particularlymanner, a function or operation specified in a specific block may beperformed differently from the flow specified in a flowchart, flowdiagram, etc. For example, functions or operations illustrated as beingperformed serially in two consecutive blocks may actually be performedsimultaneously, or in some cases be performed in reverse order.

According to one or more example embodiments, computer processingdevices may be described as including various functional units thatperform various operations and/or functions to increase the clarity ofthe description. However, computer processing devices are not intendedto be limited to these functional units. For example, in one or moreexample embodiments, the various operations and/or functions of thefunctional units may be performed by other ones of the functional units.Further, the computer processing devices may perform the operationsand/or functions of the various functional units without sub-dividingthe operations and/or functions of the computer processing units intothese various functional units.

Units and/or devices according to one or more example embodiments mayalso include one or more storage devices. The one or more storagedevices may be tangible or non-transitory computer-readable storagemedia, such as random access memory (RAM), read only memory (ROM), apermanent mass storage device (such as a disk drive), solid state (e.g.,NAND flash) device, and/or any other like data storage mechanism capableof storing and recording data. The one or more storage devices may beconfigured to store computer programs, program code, instructions, orsome combination thereof, for one or more operating systems and/or forimplementing the example embodiments described herein. The computerprograms, program code, instructions, or some combination thereof, mayalso be loaded from a separate computer readable storage medium into theone or more storage devices and/or one or more computer processingdevices using a drive mechanism. Such separate computer readable storagemedium may include a Universal Serial Bus (USB) flash drive, a memorystick, a Blu-ray/DVD/CD-ROM drive, a memory card, and/or other likecomputer readable storage media. The computer programs, program code,instructions, or some combination thereof, may be loaded into the one ormore storage devices and/or the one or more computer processing devicesfrom a remote data storage device via a network interface, rather thanvia a local computer readable storage medium. Additionally, the computerprograms, program code, instructions, or some combination thereof, maybe loaded into the one or more storage devices and/or the one or moreprocessors from a remote computing system that is configured to transferand/or distribute the computer programs, program code, instructions, orsome combination thereof, over a network. The remote computing systemmay transfer and/or distribute the computer programs, program code,instructions, or some combination thereof, via a wired interface, an airinterface, and/or any other like medium.

The one or more hardware devices, the one or more storage devices,and/or the computer programs, program code, instructions, or somecombination thereof, may be specially designed and constructed for thepurposes of the example embodiments, or they may be known devices thatare altered and/or modified for the purposes of example embodiments.

A hardware device, such as a computer processing device, may run anoperating system (OS) and one or more software applications that run onthe OS. The computer processing device also may access, store,manipulate, process, and create data in response to execution of thesoftware. For simplicity, one or more example embodiments may beexemplified as a computer processing device or processor; however, oneskilled in the art will appreciate that a hardware device may includemultiple processing elements or processors and multiple types ofprocessing elements or processors. For example, a hardware device mayinclude multiple processors or a processor and a controller. Inaddition, other processing configurations are possible, such as parallelprocessors.

The computer programs include processor-executable instructions that arestored on at least one non-transitory computer-readable medium (memory).The computer programs may also include or rely on stored data. Thecomputer programs may encompass a basic input/output system (BIOS) thatinteracts with hardware of the special purpose computer, device driversthat interact with particular devices of the special purpose computer,one or more operating systems, user applications, background services,background applications, etc. As such, the one or more processors may beconfigured to execute the processor executable instructions.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language) or XML (extensible markuplanguage), (ii) assembly code, (iii) object code generated from sourcecode by a compiler, (iv) source code for execution by an interpreter,(v) source code for compilation and execution by a just-in-timecompiler, etc. As examples only, source code may be written using syntaxfrom languages including C, C++, C #, Objective-C, Haskell, Go, SQL, R,Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5,Ada, ASP (active server pages), PHP, Scala, Eiffel, Smalltalk, Erlang,Ruby, Flash®, Visual Basic®, Lua, and Python®.

Further, at least one embodiment of the invention relates to thenon-transitory computer-readable storage medium including electronicallyreadable control information (processor executable instructions) storedthereon, configured in such that when the storage medium is used in acontroller of a device, at least one embodiment of the method may becarried out.

The computer readable medium or storage medium may be a built-in mediuminstalled inside a computer device main body or a removable mediumarranged so that it can be separated from the computer device main body.The term computer-readable medium, as used herein, does not encompasstransitory electrical or electromagnetic signals propagating through amedium (such as on a carrier wave); the term computer-readable medium istherefore considered tangible and non-transitory. Non-limiting examplesof the non-transitory computer-readable medium include, but are notlimited to, rewriteable non-volatile memory devices (including, forexample flash memory devices, erasable programmable read-only memorydevices, or a mask read-only memory devices); volatile memory devices(including, for example static random access memory devices or a dynamicrandom access memory devices); magnetic storage media (including, forexample an analog or digital magnetic tape or a hard disk drive); andoptical storage media (including, for example a CD, a DVD, or a Blu-rayDisc). Examples of the media with a built-in rewriteable non-volatilememory, include but are not limited to memory cards; and media with abuilt-in ROM, including but not limited to ROM cassettes; etc.Furthermore, various information regarding stored images, for example,property information, may be stored in any other form, or it may beprovided in other ways.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. Shared processor hardware encompasses asingle microprocessor that executes some or all code from multiplemodules. Group processor hardware encompasses a microprocessor that, incombination with additional microprocessors, executes some or all codefrom one or more modules. References to multiple microprocessorsencompass multiple microprocessors on discrete dies, multiplemicroprocessors on a single die, multiple cores of a singlemicroprocessor, multiple threads of a single microprocessor, or acombination of the above.

Shared memory hardware encompasses a single memory device that storessome or all code from multiple modules. Group memory hardwareencompasses a memory device that, in combination with other memorydevices, stores some or all code from one or more modules.

The term memory hardware is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium is therefore considered tangible and non-transitory. Non-limitingexamples of the non-transitory computer-readable medium include, but arenot limited to, rewriteable non-volatile memory devices (including, forexample flash memory devices, erasable programmable read-only memorydevices, or a mask read-only memory devices); volatile memory devices(including, for example static random access memory devices or a dynamicrandom access memory devices); magnetic storage media (including, forexample an analog or digital magnetic tape or a hard disk drive); andoptical storage media (including, for example a CD, a DVD, or a Blu-rayDisc). Examples of the media with a built-in rewriteable non-volatilememory, include but are not limited to memory cards; and media with abuilt-in ROM, including but not limited to ROM cassettes; etc.Furthermore, various information regarding stored images, for example,property information, may be stored in any other form, or it may beprovided in other ways.

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks andflowchart elements described above serve as software specifications,which can be translated into the computer programs by the routine workof a skilled technician or programmer.

Although described with reference to specific examples and drawings,modifications, additions and substitutions of example embodiments may bevariously made according to the description by those of ordinary skillin the art. For example, the described techniques may be performed in anorder different with that of the methods described, and/or componentssuch as the described system, architecture, devices, circuit, and thelike, may be connected or combined to be different from theabove-described methods, or results may be appropriately achieved byother components or equivalents.

At least one embodiment is directed to a current sensor unit,comprising:

a rectification module, configured to convert an AC current to a pulsedDC current;

a power source conversion module containing an energy storage element,connected to the rectification module and configured to store energy forthe energy storage element based upon the pulsed DC current duringoperation in a charging mode and to generate a power supply currentbased upon a voltage of the energy storage element;

a mode switching module, connected to the rectification module andconfigured to be bypassed by the power source conversion module duringoperation in the charging mode, and to bypass the power sourceconversion module during operation in an energy release mode;

a current sensor module, connected to the rectification module, thepower source conversion module and the mode switching module separatelyand configured to detect a pulsed DC current flowing back from the powersource conversion module or a pulsed DC current flowing back from themode switching module;

a control module, configured to acquire electrical energy from the powersupply current, determine that operation is in the charging mode or theenergy release mode based upon the voltage of the energy storageelement, and acquire a first detection value that is provided by thecurrent sensor module and relates to a pulsed DC current; and

a self-calibration module, configured to generate a predeterminedcurrent flowing through the current sensor module in a self-calibrationprocess;

wherein the current sensor module is further configured to detect thepredetermined current; and the control module is further configured tocalibrate the first detection value based upon a second detection valuethat is provided by the current sensor module and relates to thepredetermined current.

As can be seen, in an embodiment of the present invention, the currentsensor unit can continuously detect current, and thereby effectivelyprevent a sudden current change event; moreover, the supply of power isnot continuous, so sampling precision can be improved and high powerconsumption can be prevented. In addition, the current sensor unitfurther has a self-calibration function, thereby ensuring themeasurement precision after long-term use in harsh conditions (e.g. hightemperature and high humidity).

In one embodiment, also included is:

a signal conditioning module, arranged between the current sensor moduleand the control module, and configured to acquire electrical energy fromthe power supply current and to condition the first detection value andthe second detection value.

Thus, the signal conditioning module in an embodiment of the presentinvention can acquire electrical energy from the power supply current,and by subjecting the detection value to signal conditioning, can alsoamplify and strengthen the detection value, converting the detectionvalue to a voltage signal that can be conditioned by the control module,making it easier for the control module to perform signal processing.

In one embodiment, the control module is configured to determine thatoperation is in the energy release mode when the voltage of the energystorage element is greater than or equal to a first predetermined value,and to determine that operation is in the charging mode when the voltageof the energy storage element is lower than or equal to a secondpredetermined value, wherein the first predetermined value is greaterthan the second predetermined value.

Thus, the control module in an embodiment of the present invention cancontrol the specific operating mode based upon the size of the voltageof the energy storage element.

In one embodiment, the control module is configured to calculate acalibration factor based upon the second detection value and atheoretical value of the predetermined current, and to calibrate thefirst detection value based upon the calibration factor.

Thus, an embodiment of the present invention can conveniently calculatethe calibration factor, and conveniently calibrate the first detectionvalue using the calibration factor.

In one embodiment, the control module is further configured to abandon acalibration factor that is greater than a first predetermined thresholdor less than a second predetermined threshold, wherein the firstpredetermined threshold is greater than the second predeterminedthreshold.

As can be seen, an embodiment of the present invention can also screenout inaccurate calibration factors.

In one embodiment, the self-calibration module comprises:

a first switch;

a diode, an anode of the diode being connected to the rectificationmodule;

a capacitor, a first end of the capacitor being connected to a cathodeof the diode;

a second switch, connected to a second end of the capacitor;

a voltage control current source, connected in parallel with thecapacitor; and

a third switch, arranged between the voltage control current source andthe current sensor module.

As can be seen, an embodiment of the present invention also proposes aself-calibration module that uses a capacitor to provide a voltage for avoltage control current source.

In one embodiment, the rectification module comprises a full-bridgerectification circuit or a half-bridge rectification circuit; and therectification module further comprises:

a transient voltage suppression element, connected in parallel with thefull-bridge rectification circuit or half-bridge rectification circuit.

As can be seen, the rectification module in an embodiment of the presentinvention has more than one form of circuit arrangement, and can alsosuppress transient voltages.

A current detection circuit, comprising:

a current transformer, containing a primary-side circuit and asecondary-side circuit;

a current sensor unit, connected to an output terminal of thesecondary-side circuit, wherein the current sensor unit comprises: arectification module, configured to convert an AC current outputted bythe secondary-side circuit via the output terminal to a pulsed DCcurrent; a power source conversion module containing an energy storageelement, connected to the rectification module and configured to storeenergy for the energy storage element based upon the pulsed DC currentduring operation in a charging mode and to generate a power supplycurrent based upon a voltage of the energy storage element; a modeswitching module, connected to the rectification module and configuredto be bypassed by the power source conversion module during operation inthe charging mode, and to bypass the power source conversion moduleduring operation in an energy release mode; a current sensor module,connected to the rectification module, the power source conversionmodule and the mode switching module separately and configured to detecta pulsed DC current flowing back from the power source conversion moduleor a pulsed DC current flowing back from the mode switching module; acontrol module, configured to acquire electrical energy from a powersupply current, determine that operation is in the charging mode or theenergy release mode based upon the voltage of the energy storageelement, and acquire a first detection value that is provided by thecurrent sensor module and relates to a pulsed DC current; aself-calibration module, configured to generate a predetermined currentflowing through the current sensor module in a self-calibration process;wherein the current sensor module is further configured to detect thepredetermined current; and the control module is further configured tocalibrate the first detection value based upon a second detection valuethat is provided by the current sensor module and relates to thepredetermined current.

Thus, an embodiment of the present invention also realizes a currentdetection circuit for a current transformer, which can continuouslydetect current, and thereby effectively prevent a sudden current changeevent; moreover, the supply of power is not continuous, so samplingprecision can be improved and high power consumption can be prevented.In addition, the current sensor unit further has a self-calibrationfunction, thereby ensuring the measurement precision after long-term usein harsh conditions (e.g. high temperature and high humidity).

In one embodiment, the self-calibration module comprises:

a first switch;

a diode, an anode of the diode being connected to the rectificationmodule;

a capacitor, a first end of the capacitor being connected to a cathodeof the diode;

a second switch, connected to a second end of the capacitor;

a voltage control current source, connected in parallel with thecapacitor; and

a third switch, arranged between the voltage control current source andthe current sensor module.

Thus, an embodiment of the present invention also proposes aself-calibration module that uses a capacitor to provide a voltage for avoltage control current source.

In one embodiment, the control module is configured to calculate acalibration factor based upon the second detection value and atheoretical value of the predetermined current, and to calibrate thefirst detection value based upon the calibration factor.

Thus, an embodiment of the present invention can conveniently calculatethe calibration factor, and conveniently calibrate the first detectionvalue using the calibration factor.

The present invention is explained in further detail below inconjunction with the accompanying drawings and embodiments, to clarifythe technical solution and advantages thereof. It should be understoodthat the particular embodiments described here are merely intended toexplain the present invention elaboratively, not to define the scope ofprotection thereof.

The solution of the present invention is expounded below by describing anumber of representative embodiments, in order to make the descriptionconcise and intuitive. The large number of details in the embodimentsare merely intended to assist with understanding of the solution of thepresent invention. However, obviously, the technical solution of thepresent invention need not be limited to these details when implemented.To avoid making the solution of the present invention confusedunnecessarily, some embodiments are not described meticulously, butmerely outlined. Hereinbelow, “comprises” means “including but notlimited to”, while “according to . . . ” means “at least according to .. . , but not limited to only according to . . . ”. In line with thelinguistic customs of Chinese, in cases where the quantity of acomponent is not specified hereinbelow, this means that there may be oneor more of the component; this may also be interpreted as meaning atleast one.

In an embodiment of the present invention, a current sensor unit havinga novel structure is proposed. The current sensor unit can continuouslydetect current, and thereby effectively prevent a sudden current changeevent; moreover, the supply of power is not continuous, so samplingprecision can be improved and high power consumption can be prevented.

FIG. 3 is a demonstrative structural diagram of the current sensor unitof the present invention.

As shown in FIG. 3, the current sensor unit 300 comprises:

a rectification module 301, configured to convert an AC current to apulsed DC current;

a power source conversion module 302 containing an energy storageelement (not shown in FIG. 3, preferably containing a capacitor),connected to the rectification module 301 and configured to store energyfor the energy storage element based upon the pulsed DC current when thecurrent sensor unit 300 is operating in a charging mode and to generatea power supply current based upon a voltage of the energy storageelement;

a mode switching module 303, connected to the rectification module 301and configured to be bypassed by the power source conversion module 302when the current sensor unit 300 is operating in the charging mode, andto bypass the power source conversion module 302 when the current sensorunit 300 is operating in an energy release mode;

a current sensor module 304, connected to the rectification module 301,the power source conversion module 302 and the mode switching module 303separately and configured to detect a pulsed DC current flowing backfrom the power source conversion module 302 or a pulsed DC currentflowing back from the mode switching module 303;

a control module 305, configured to acquire electrical energy from thepower supply current, acquire a detection value provided by the currentsensor module 304 (i.e. a detection value for a pulsed DC currentflowing through the current sensor module 304), and determine that thecurrent sensor unit 300 operates in the charging mode or energy releasemode based upon the voltage of the energy storage element.

Preferably, the following factors are taken into account:

(1) a detection value signal provided by the current sensor module 304is itself relatively weak, and requires strengthening by amplification;

(2) a voltage range of the detection value signal provided by thecurrent sensor module 304 generally does not meet a voltage inputrequirement of a subsequent module;

(3) noise in the detection value signal provided by the current sensormodule 304 must be filtered out.

Thus, in an embodiment of the present invention, the detection valuesignal provided by the current sensor module 304 also undergoes signalconditioning.

In one embodiment, the current sensor unit 300 further comprises asignal conditioning module 306. The signal conditioning module 306 isarranged between the current sensor module 304 and the control module305, and configured to acquire electrical energy from the power supplycurrent and to condition the detection value provided by the currentsensor module 304.

Preferably, the signal conditioning module 306 may contain various typesof power amplifier structure, to subject the detection value signalprovided by the current sensor module 304 to power amplification. Thesignal conditioning module 306 may further contain a noise filteringelement; the embodiments of the present invention do not impose anyrestrictions in this regard.

The current sensor unit in FIG. 3 is connected to a current transformer.The current transformer contains a primary-side circuit 401 and asecondary-side circuit 402. Based on the principle of electromagneticinduction, the current transformer converts a large current in theprimary-side circuit 401 to a small current in the secondary-sidecircuit 402, in order to be measured by the current sensor unit 300. Thecurrent transformer may consist of a closed core and a winding. Ingeneral, the primary-side circuit 401 has a very small number of windingturns, and is series-connected in a current line requiring measurement,therefore it often has the entire current of the line flowing throughit; the secondary-side circuit 402 has a relatively large number ofwinding turns, and is series-connected with the current sensor unit.

In FIG. 3, the rectification module 301 is connected to an outputterminal of the secondary-side circuit 402 of the current transformer.The rectification module 301 converts an AC current outputted via theoutput terminal by the secondary-side circuit 402 to a pulsed DCcurrent.

In one embodiment, the rectification module 301 comprises a full-bridgerectification circuit or a half-bridge rectification circuit; and therectification module 301 further comprises a transient voltagesuppression element (not shown in FIG. 3). The transient voltagesuppression element is connected in parallel with the full-bridgerectification circuit or half-bridge rectification circuit. Preferably,the transient voltage suppression element may be implemented as atransient voltage suppressor (TVS) or a varistor, etc.

In one embodiment, the power source conversion module 302 may contain aswitching power source or a linear power source. Preferably, ananti-reverse diode is configured at a frontmost end of the power sourceconversion module 302, to prevent energy of a rear-end power source frombeing released in a reverse direction when the mode switching module 303is bypassed. At the same time, since the anti-return diode has aconduction switch-on voltage, a front-end current will also be blockedby the anti-return diode and will not flow into the power sourceconversion module 302, so as to ensure the effectiveness of the bypassfunction. Furthermore, the energy storage element contained in the powersource conversion module 302 may be used to provide energy required by aload when charging is not taking place.

The energy storage element in the power source conversion module 302 maybe implemented as a capacitor. Moreover, the power source conversionmodule 302 may further comprise: an anti-return diode; a Buck circuit,connected to the anti-return diode, and capable of outputting acontinuous power supply current based upon electrical energy stored inthe energy storage element; a first resistor, connected to the Buckcircuit and the anti-return diode separately; a second resistor,connected to the first resistor; wherein a connection point of the firstresistor and second resistor is connected to a signal detection end ofthe control module 305.

The specific circulation path of the pulsed DC current outputted by therectification module 301 may be controlled by the mode switching module303.

Specifically:

(1) When the mode switching module 303 is bypassed by the power sourceconversion module 302 (this corresponds to the current sensor unit 300operating in the charging mode), the pulsed DC current will not flowthrough the mode switching module 303, but will flow in its entiretyfrom the rectification module 301 to the power source conversion module302. The voltage of the energy storage element contained in the powersource conversion module 302 will rise, and the electrical energyprovided by the pulsed DC current is stored.

Moreover, the power source conversion module 302 also generates a powersupply current based upon the voltage of the energy storage element.This power supply current is provided to electronic components that needto be provided with electrical energy in the current sensor unit 300,for example provided to the control module 305 and the signalconditioning module 306, so as to provide electrical energy to thecontrol module 305 and the signal conditioning module 306. The powersource conversion module 302 is also connected to the current sensormodule 304. The pulsed DC current flows to the current sensor module 304from the power source conversion module 302. The current sensor module304 can detect the pulsed DC current. The pulsed DC current then flowsback to the current transformer from the current sensor module 304.

As shown by the current loop 403 during operation in the charging modein FIG. 3, in the charging mode, the loop of the pulsed DC currentcomprises: secondary-side circuit 402 of currenttransformer->rectification module 301->power source conversion module302->current sensor module 304->secondary-side circuit 402 of currenttransformer.

During charging in the charging mode, the current flowing through thecurrent sensor module 304 can reflect a primary-side current of thecurrent transformer. Although this kind of reflection relationship mightnot be completely correct due to current fluctuation during charging, itcan serve as a basis for determining a sudden change in the primary-sidecurrent. Thus, the charging mode can be regarded as a non-precisesampling process for the primary-side current of the currenttransformer.

(2) When the mode switching module 303 bypasses the power sourceconversion module 302 (this corresponds to the current sensor unit 300operating in the energy release mode), the pulsed DC current will notflow through the power source conversion module 302, but will flow inits entirety from the rectification module 301 to the mode switchingmodule 303. The mode switching module 303 is also connected to thecurrent sensor module 304. The pulsed DC current also flows from themode switching module 303 to the current sensor module 304. The currentsensor module 304 can detect the pulsed DC current. The pulsed DCcurrent then flows back to the current transformer from the currentsensor module 304.

In the energy release mode, the power source conversion module 302 stillgenerates a power supply current based upon the voltage of the energystorage element contained in the power source conversion module 302 (thecurrent sensor unit 300 was previously operating in the charging mode).This power supply current is provided to electronic components that needto be provided with electrical energy in the current sensor unit 300,for example provided to the control module 305 and the signalconditioning module 306, so as to provide electrical energy to thecontrol module 305 and the signal conditioning module 306.

In the energy release mode, all of the current outputted by the currenttransformer flows through the mode switching module 303, and istransmitted back to the current transformer via the current sensormodule 304. Thus, a current transformer primary-side current valuedetected via the current sensor module 304 is accurate. Moreover, aninput-end voltage of the power source conversion module 302 no longerrises, i.e. surplus energy exceeding a predetermined voltage isreleased, thereby ensuring that a rear-end device will not be damageddue to overvoltage; at the same time, a release loop through therectification module 301 containing the transient voltage suppressionelement, the mode switching module 303 and the current sensor module 304causes the secondary-side voltage of the current transformer to belower. The same current is released, and the lower released voltageensures that a release power consumption of the secondary side of thecurrent transformer is lower.

As shown by the current loop 404 during operation in the energy releasemode in FIG. 3, in the energy release mode, the loop through which thepulsed DC current flows comprises: secondary-side circuit 402 of currenttransformer->rectification module 301->mode switching module303->current sensor module 304->secondary-side circuit 402 of currenttransformer.

As can be seen, since the current sensor module 304 is arranged on acommon path of the loop of the pulsed DC current in the charging modeand the loop of the pulsed DC current in the energy release mode, thecurrent sensor module 304 can detect a current outputted by the currenttransformer regardless of whether the current sensor unit 300 is in theenergy release mode or the charging mode, thus the detection of currentis continuous, and can be used as a basis for determining a suddenchange in the primary-side current.

In one embodiment, the control module 305 is configured to determinethat the current sensor unit 300 operates in the energy release modewhen the voltage of the energy storage element in the power sourceconversion module 302 is greater than or equal to a first predeterminedvalue, at which time the mode switching module 303 bypasses the powersource conversion module 302; and to determine that the current sensorunit 300 operates in the charging mode when the voltage of the energystorage element in the power source conversion module 302 is lower thanor equal to a second predetermined value, at which time the modeswitching module 303 is bypassed by the power source conversion module302, wherein the first predetermined value is greater than the secondpredetermined value.

Preferably, the mode switching module 303 may be implemented as ametal-oxide semiconductor field effect transistor (MOS) or a bipolarjunction transistor; the current sensor module 304 may be implemented asa resistor configured to convert a current signal to a voltage signal,or as another type of current sensor, e.g. a Hall element, etc.

In one embodiment, the control module 305 is further configured tocalculate an output value based upon the detection value; the currentsensor unit 300 further comprises: an output module 307, configured tooutput the output value by wired communication or wirelesscommunication. The output module 307 may be implemented as a separateelement connected to the control module 305, or be integrated with thecontrol module 305.

For example, when the AC current received by the rectification module301 is the secondary-side current of the current transformer, thecontrol module 305 calculates a primary-side current value according toa predetermined conversion relation (e.g. a number-of-turns ratiobetween the primary side and secondary side of the current transformer),and uses this primary-side current value as the output value. The outputmodule 307 receives the output value from the control module 305, andsends the output value to a receiving side via a wired interface orwireless interface. For example, the wired interface comprises at leastone of the following: a universal serial bus interface, controller localarea network interface or serial port, etc.; the wireless interfacecomprises at least one of the following: an infrared interface, nearfield communication interface, Bluetooth interface, Zigbee interface,wireless broadband interface, etc.

The control module 305 may be implemented as comprising one or morecentral processors or one or more field-programmable gate arrays,wherein the field-programmable gate array integrates one or more centralprocessor cores. Specifically, the central processor or centralprocessor core may be implemented as a CPU, MCU or digital signalprocessor (DSP), etc. Preferably, the control module 305 may furthercomprise a human-machine interface (HMI), and a user instructionrelating to output value transmission, etc. can be received via the HMI.

As can be seen, in the circuit architecture of embodiments of thepresent invention, only one current transformer need be used. Therectification module 301 converts the AC outputted by the currenttransformer to a pulsed DC current, and the circulation path of thepulsed DC current is controlled by the mode switching module 303.

When the current sensor unit 300 is in the charging mode, the flowdirection of the pulsed DC current is as indicated by the current loop403. At this time, the whole of the pulsed DC current is inputted to thepower source conversion module 302, and the power source conversionmodule 302 can provide electrical energy for the subsequent signalconditioning module 306, control module 305 and output module 307, etc.based upon the pulsed DC current. Specifically, the voltage of theenergy storage element contained in the power source conversion module302 is raised by the pulsed DC current, and the energy storage elementstores the electrical energy provided by the pulsed DC current.

Moreover, the power source conversion module 302 also generates a powersupply current based upon the voltage of the energy storage element.This power supply current is provided to electronic components that needto be provided with electrical energy in the current sensor unit 300,for example provided to the control module 305, signal conditioningmodule 306 and output module 307. Furthermore, the pulsed DC currentinputted to the power source conversion module 302 flows back to thecurrent transformer through the current sensor module 304, wherein thecurrent sensor module 304 detects the pulsed DC current flowing throughitself.

When the current sensor unit 300 is in the energy release mode, the flowdirection of the pulsed DC current is as indicated by the current loop404. At this time, the whole of the pulsed DC current is inputted to themode switching module 303. Furthermore, the pulsed DC inputted to themode switching module 303 flows back to the current transformer throughthe current sensor module 304, wherein the current sensor module 304detects the pulsed DC current flowing through itself. In the energyrelease mode, the power source conversion module 302 continues togenerate a power supply current based upon the voltage of the energystorage element (the current sensor unit 300 was previously operating inthe charging mode and has stored energy). This power supply current isprovided to electronic components that need to be provided withelectrical energy in the current sensor unit 300, for example providedto the control module 305, signal conditioning module 306 and outputmodule 307, etc.

In FIG. 3, the current sensor module 304 is arranged on a common pathduring operation of the mode switching module 303 and power sourceconversion module 302. Thus, the current sensor module 304 can detect acurrent outputted by the current transformer regardless of whether thecurrent sensor unit 300 is in the energy release mode or the chargingmode, thus the detection of current is continuous, and can be used as abasis for determining a sudden change in the primary-side current.

In FIG. 3, the signal conditioning module 306 can convert the detectionvalue (generally a voltage signal) outputted by the current sensormodule 304 to a voltage signal that can be processed by the controlmodule 305. The conditioning process may be linear, and is not affectedmuch by temperature, and in particular may be implemented by anoperational amplifier. The control module 305 can calculate acorresponding current value, i.e. the primary-side current value of thecurrent transformer, based upon the voltage signal provided by thesignal conditioning module 306. Furthermore, the control module 305 alsodetermines whether operation is in the charging mode or energy releasemode based upon the voltage value of the energy storage elementcontained in the power source conversion module 302. In addition, inFIG. 3, the input-end voltage of the power source conversion module 302no longer rises when the mode switching module 303 begins the bypassingoperation, thereby ensuring that the rear end meanwhile will notexperience overvoltage and be damaged.

In an embodiment of the present invention, for a current range requiringprecise sampling, the signal conditioning module 306 can use amulti-stage amplification circuit with a gradually increasingamplification factor, wherein different amplification stages areresponsible for different current ranges.

The current sensor unit shown in FIG. 3 may be implemented by way ofvarious forms of specific circuit. For example, FIG. 4 is a firstdemonstrative circuit diagram of the current sensor unit of the presentinvention.

In FIG. 4, the mode switching module 303 is arranged at a rear end ofthe rectification module 301. The rectification module 301 comprises afull-bridge rectification circuit and a transient voltage suppressorTVS1. The mode switching module 303 comprises a MOS transistor M1; thepower source conversion module 302 comprises: an anti-return diode T1; aBuck circuit connected to the anti-return diode T1; a resistor R2,connected separately to the Buck circuit and the anti-return diode T1;and a resistor R3 connected to the resistor R2; a connection point ofthe resistor R2 and resistor R3 is connected to a signal detection end“Signal” of the control module 305; the Buck circuit is connected to apower source end VCC of the control module 305; and a capacitor C1 isconnected to the anti-return diode T1.

The control module 305 detects a voltage of the capacitor C1 based uponthe signal detection end “Signal”, determines that operation is in theenergy release mode when the voltage of the capacitor C1 is greater thanor equal to the first predetermined value, and determines that operationis in the charging mode when the voltage of the capacitor C1 is lessthan or equal to the second predetermined value, wherein the firstpredetermined value is greater than the second predetermined value.

When operation is in the charging mode, the control module 305 sends aturn-off signal to the mode switching module 303 via a control end CTR,and the MOS transistor M1 is turned off based upon the turn-off signal,such that the mode switching module 303 is bypassed by the power sourceconversion module 302. When operation is in the energy release mode, thecontrol module 305 sends a turn-on signal to the mode switching module303 via the control end CTR, and the MOS transistor M1 is turned on,based upon the turn-on signal, such that the power source conversionmodule 302 is bypassed by the mode switching module 303.

In the charging mode, the pulsed DC current outputted by therectification module 301 is inputted to the power source conversionmodule 302. The pulsed DC current is filtered by the capacitor C1, andthe capacitor at the same time also has an energy storage function. TheBuck circuit then converts the energy stored in the capacitor C1 to a DCvoltage for supplying power to the rear end. The DC voltage is outputtedto the power source end VCC of the control module 305 and to the signalconditioning module 306, so as to supply power stably to the controlmodule 305 and signal conditioning module 306. Furthermore, the pulsedDC current also flows back to the secondary side of the mutual inductorvia the current sensor module 304.

In the energy release mode, the pulsed DC current outputted by therectification module 301 is inputted to the mode switching module 303.The pulsed DC current flows back to the secondary side of the mutualinductor via the current sensor module 304. At this time, the Buckcircuit still converts the energy stored in the capacitor C1 to a DCvoltage for supplying power to the rear end. The DC voltage is outputtedto the power source end VCC of the control module 305 and to the signalconditioning module 306, so as to supply power stably to the controlmodule 305 and signal conditioning module 306.

In one embodiment, the signal conditioning module 306 in FIG. 3comprises: a first-stage operational amplifier unit, comprising anoperational amplifier connected to the current sensor module 304; asecond-stage operational amplifier unit, connected to an output end ofthe operational amplifier; wherein the second-stage operationalamplifier comprises multiple operational amplifiers connected inparallel with each other, or the second-stage operational amplifiercomprises multiple operational amplifiers connected in series with eachother. For a current range requiring precise sampling, a multi-stageop-amp circuit with a gradually increasing amplification factor can beused, to increase the resolution of current detection. For a currentrange needing to have event triggering, an op-amp circuit with a smallamplification factor and a short delay can be used.

FIG. 5 is a first demonstrative circuit diagram of the signalconditioning module of the present invention.

In FIG. 5, the signal conditioning module 306 comprises: a first-stageoperational amplifier unit, comprising an operational amplifier OPA1connected to the current sensor module 304; a second-stage operationalamplifier unit, connected to an output end of the operational amplifierOPA1; wherein the second-stage operational amplifier comprises 4operational amplifiers connected in parallel with each other,specifically an operational amplifier OPA2, an operational amplifierOPA3, an operational amplifier OPA4 and an operational amplifier OPA5.The amplification factors and delays of the operational amplifiers maybe the same or different. Thus, correspondingly, the signal conditioningmodule 306 may have 5 outputs, specifically Output1, Output2, Output3,Output4 and Output5.

FIG. 6 is a second demonstrative circuit diagram of the signalconditioning module of the present invention.

In FIG. 6, the signal conditioning module 306 comprises: a first-stageoperational amplifier unit, comprising an operational amplifier OPA1connected to the current sensor module 304; a second-stage operationalamplifier unit, connected to an output end of the operational amplifierOPA1; wherein the second-stage operational amplifier comprises 4operational amplifiers connected in series with each other, specificallyan operational amplifier OPA2, an operational amplifier OPA3, anoperational amplifier OPA4 and an operational amplifier OPA5. Theamplification factors and delays of the operational amplifiers may bethe same or different. Thus, correspondingly, the signal conditioningmodule 306 has 5 outputs, specifically Output1, Output2, Output3,Output4 and Output5.

Typical examples of the signal conditioning module have been describeddemonstratively above. Those skilled in the art will realize that such adescription is purely demonstrative, and not intended to define thescope of protection of embodiments of the present invention.

Those skilled in the art will realize that the circuit shown in FIG. 3could be subjected to various changes, deletions or omissions. All suchchanges, deletions or omissions should be included in the scope ofprotection of embodiments of the present invention.

For example, in FIG. 3, the mode switching module 303 is arranged at therear end of the rectification module 301. In fact, the mode switchingmodule 303 could also be arranged at a front end of the rectificationmodule 301.

FIG. 7 is a second demonstrative circuit diagram of the current sensorunit of the present invention. As shown in FIG. 7, the mode switchingmodule 303 is arranged at the front end of the rectification module 301.

The applicant has also made the following discovery: for the currentsensor unit connected to a single current transformer as shown in FIG.3, the secondary-side output of the current transformer is a currentsignal; the current signal outputted at the secondary side of thecurrent transformer is converted to a voltage signal using the currentsensor module 304 that is generally implemented as a resistor or Hallsensor, and the voltage signal passes through the signal conditioningmodule 306 containing an operational amplifier before being outputted tothe control module 305. For application environments with highmeasurement precision requirements, neither temperature drift norlifespan attenuation of the resistor or Hall sensor can be ignored.Although a low-temperature-drift device can generally be chosen to solvethe problem of temperature drift, the problem of lifespan attenuation isdifficult to solve. Thus, the question of how to guarantee the precisionof the current sensor module 304 after long-term use in harsh conditions(e.g. high temperature and high humidity) is a challenge.

To solve this technical problem, an embodiment of the present inventionfurther proposes a current sensor unit with a self-calibration function.

FIG. 8 is a demonstrative structural diagram of the current sensor unitwith a self-calibration function according to the present invention.Compared with the current sensor unit shown in FIG. 3, the currentsensor unit in FIG. 8 further contains a self-calibration module 308,and further has a self-calibration function.

Specifically, as shown in FIG. 8, the current sensor unit 300 comprises:

a rectification module 301, configured to convert an AC current to apulsed DC current;

a power source conversion module 302 containing an energy storageelement (not shown in FIG. 8, preferably containing a capacitor),connected to the rectification module 301 and configured to store energyfor the energy storage element based upon the pulsed DC current when thecurrent sensor unit 300 is operating in a charging mode and to generatea power supply current based upon a voltage of the energy storageelement;

a mode switching module 303, connected to the rectification module 301and configured to be bypassed by the power source conversion module 302when the current sensor unit 300 is operating in the charging mode, andto bypass the power source conversion module 302 when the current sensorunit 300 is operating in an energy release mode;

a current sensor module 304, connected to the rectification module 301,the power source conversion module 302 and the mode switching module 303separately and configured to detect a pulsed DC current flowing backfrom the power source conversion module 302 or a pulsed DC currentflowing back from the mode switching module 303;

a control module 305, configured to acquire electrical energy from thepower supply current, acquire a first detection value that is providedby the current sensor module 304 and relates to a pulsed DC current(i.e. a detection value for a pulsed DC current flowing through thecurrent sensor module 304), and determine that the current sensor unit300 operates in the charging mode or energy release mode based upon thevoltage of the energy storage element;

a self-calibration module 308, configured to generate a predeterminedcurrent flowing through the current sensor module 304 in aself-calibration process;

wherein the current sensor module 304 is further configured to detectthe predetermined current; and the control module 305 is furtherconfigured to calibrate the first detection value based upon a seconddetection value that is provided by the current sensor module 304 andrelates to the predetermined current.

Compared with the various modules in the current sensor unit shown inFIG. 3, the corresponding modules in the current sensor unit in FIG. 8have similar functions, which are not described again in embodiments ofthe present invention. Compared with the current sensor unit shown inFIG. 3, the current sensor unit in FIG. 8 further has the followingcharacteristic: when the control module 305 in the current sensor unitin FIG. 8 discovers that a predetermined self-calibration condition ismet (e.g. a continuous operating time of the current sensor unit 300reaches a predetermined time threshold), the current sensor unit 300enters the self-calibration process. Otherwise, when the control module305 of the current sensor unit in FIG. 8 discovers that thepredetermined self-calibration condition is not met, the current sensorunit 300 is in a non-self-calibration process. Here:

(1) When the current sensor unit is in the non-self-calibration process(including the charging mode and the energy release mode), the pulsed DCcurrent outputted by the rectification module 301 does not flow throughthe self-calibration module 308, at which time the self-calibrationmodule 308 corresponds to an open-circuit state. For the specificprocessing procedures of the charging mode and energy release mode,please refer to FIG. 3 and the corresponding detailed description above.

(2) When the current sensor unit 300 is in the self-calibration process,the pulsed DC current outputted by the rectification module 301 flowsdirectly back to the current transformer via the self-calibration module308. Moreover, the self-calibration module 308 generates a predeterminedcurrent flowing through the current sensor module 304. The currentsensor module 304 detects the predetermined current; the control module305 calibrates the first detection value generated in the charging modeand energy release mode, based upon the second detection value that isprovided by the current sensor module 304 and relates to thepredetermined current.

Due to the presence of the energy storage element in the power sourceconversion module 302, the control module 305 and signal conditioningmodule 306 can also be in an operating state continuously in theself-calibration process. The signal conditioning module 306 acquireselectrical energy from the power supply current, and conditions thefirst detection value and second detection value. Based on the seconddetection value and a theoretical value of the predetermined current,the control module 305 calculates a calibration factor, and calibratesthe first detection value based upon the calibration factor. Preferably,the control module 305 also abandons a calibration factor that isgreater than a first predetermined threshold or less than a secondpredetermined threshold, wherein the first predetermined threshold isgreater than the second predetermined threshold.

FIG. 9 is a demonstrative circuit diagram of the current sensor unitwith a self-calibration function according to the present invention.FIG. 10 is a demonstrative flow chart of the self-calibration process ofthe current sensor unit in FIG. 9.

As can be seen in FIG. 9, the self-calibration module 308 comprises: afirst switch Q1; a diode D1, wherein an anode of the diode D1 isconnected to the rectification module 301; a capacitor C2, wherein afirst end of the capacitor C2 is connected to a cathode of the diode D1;a second switch Q2, connected to a second end of the capacitor C2; avoltage control current source VCCS, connected in parallel with thecapacitor C2; and a third switch Q3, arranged between the voltagecontrol current source VCCS and the current sensor module 304.

When the control module 306 determines that the preset self-calibrationcondition has not been met, the current sensor unit is in anon-self-calibration process. In the non-self-calibration process, thecontrol module 306 controls the first switch Q1, second switch Q2 andthird switch Q3 so as to all be OFF. At this time, the self-calibrationmodule 308 corresponds to an open-circuit state, and will not affectnormal operation of the energy release mode or charging mode.

Furthermore, when the control module 306 determines that the presetself-calibration condition has been met, the current sensor unit entersthe self-calibration process. First of all, the control module 306controls the second switch Q2 so as to be ON, thus the capacitor C2begins charging, and due to the reverse-blocking action of the diode D1,the energy of the capacitor C2 will not be released to the outside ofthe self-calibration module 308. Since the voltages of the capacitor C2and the energy storage element C1 in the power source conversion module302 are approximately equal, the control module 305 detects the voltageof the energy storage element C1 in the power source conversion module302 via a Signal port, and the control module 305 can indirectlyascertain the voltage of the capacitor C2.

When the voltage of the capacitor C2 rises to a predetermined valueV_(calibration), the control module 305 controls the first switch Q1 soas to be ON in order to cut off the effect of the primary-side currentof the current transformer on the self-calibration module 308, at whichtime the pulsed DC current outputted by the rectification module 301flows directly back to the current transformer via the self-calibrationmodule 308. Immediately after, the rectification module 301 controls thethird switch Q3 so as to be ON, leading an output current of the voltagecontrol current source VCCS (i.e. a self-calibration current) into thecurrent sensor module 304.

At the same time, due to the presence of the energy storage element C1in the power source conversion module 302, the control module 305 andsignal conditioning module 306 can also be in an operating statecontinuously in the self-calibration process; thus, the control module306 can obtain the voltage signal that results when the output currentflows through the current sensor module 304, can obtain a current valueI_(now) thereof by calculation, and by comparing I_(now) with an idealcurrent value I_(factory) corresponding to the output current, canobtain a calibration factor K, wherein K=(I_(now)/I_(factory)), and canthen use the calibration factor K to calibrate a detection valueobtained in the non-self-calibration process (e.g. taking the product ofthe calibration factor K and the detection value obtained in thenon-self-calibration process to be a final detection value), therebyreducing the measurement error. Any calibration factor that exceeds apredetermined range is not used. Moreover, to avoid accidental events,multiple determinations are performed for calibration errors.

FIG. 10 is a demonstrative flow chart of the self-calibration process ofthe current sensor unit in FIG. 9.

As shown in FIG. 10, the self-calibration process comprises:

Step 900: start.Step 901: determine whether preset self-calibration condition is met. Ifso, perform step 902 and subsequent steps; otherwise perform step 916 toend the procedure.Step 902: control module turns second switch Q2 ON.Step 903: determine whether voltage of capacitor C2 is greater thanpredetermined value V_(calibration); if so, perform step 904 andsubsequent steps, otherwise return and perform step 903 again.Step 904: control module turns first switch Q1 ON.Step 905: control module turns third switch Q3 ON, voltage controlcurrent source VCCS outputs current into current sensor module.Step 906: acquire detection value I_(now) relating to voltage signal ofcurrent sensor module.Step 907: calculate calibration factor K, whereinK=(I_(now)/I_(factory)); I_(factory) is ideal current value of outputcurrent.Step 908: determine whether calibration factor K is within predeterminedrange; if so, perform step 910 and subsequent steps, otherwise performstep 913 and subsequent steps.Step 909: set “falure” sign for number of failures to zero.Step 910: determine that calibration is successful.Step 911: turn first switch Q1, second switch Q2 and third switch Q3OFF, and perform step 916 to end the procedure.Step 912: set calibration factor K to 1, and add 1 to “falure” sign fornumber of failures.Step 913: determine whether “falure” sign for number of failures isgreater than predetermined value N; if so, perform step 914 andsubsequent steps, otherwise perform step 915 and subsequent steps.Step 914: determine that calibration has failed, and perform step 911and subsequent step.Step 915: turn first switch Q1, second switch Q2 and third switch Q3OFF, and return to perform step 901.

Step 916: end.

The voltage control current source can be realized by more than oneparticular method of implementation. FIG. 11 is a first demonstrativecircuit diagram of the voltage control current source of the presentinvention.

In FIG. 11, the diode D2 is a bandgap voltage reference chip havingtemperature compensation, with very small stable value temperature drift(if further consideration is given to cost, a bandgap reference voltagein the control module 305 can also be shared). Current limiting by acurrent-limiting resistor R21 ensures that the bandgap voltage referencechip operates in a normal mode, with a stable value of Vref.

When the resistance values of a resistor R22, a resistor R23, a resistorR24 and a resistor R25 are equal, resistor R22 is much greater than aresistor R26 and the third switch Q3 is ON, then a common-end voltage ofresistor R25 and resistor R26 is approximately equal to 0 volts, thus anoutput voltage U1 of the voltage control current source (including apower amplifier and peripheral circuitry thereof) has the followingequation: U1=[Vref*R25/(R24+R25)]*(R22+R23)/R22=Vref. Thus: a voltagedifference arising across resistor R26 set for the output current isequal to Vref. A current flowing through resistor R26 is Iout, whereinIout=Vref/R26. It must be pointed out that: if resistor R22, resistorR23, resistor R24 and resistor R25 are of the same type, then theeffects of temperature and lifespan can be mutually compensated, thusreducing the effect of resistance on the long-term uniformity of thiscircuit.

In one embodiment, an input voltage of the voltage control currentsource can be altered dynamically, e.g. using a DA interface of thecontrol module, multiple different self-calibration currents can beoutputted, which is beneficial for a sampling circuit with zero-pointdrift.

FIG. 12 is a second demonstrative circuit diagram of the voltage controlcurrent source of a embodiment of the present invention.

In FIG. 11, if the impedance of the current sensor module 304 is 0.5ohms and an output voltage of 5 millivolts (mV) must be produced inorder to calibrate the circuit, then the output current of the voltagecontrol current source must be 10 milliamps (mA). Thus, the followingselection can be made: Vref=1 V, resistor R26 is 100 ohms, and theresistance values of resistors R22, R23, R24 and R25 are equal andgreater than 10 kiloohms; and 10 kiloohms is much greater than theresistance value of resistor R26. The value of resistor R21 can besufficiently large, within the stable range of diode D2, to reduceconsumption of the energy of capacitor C2, such that the energy ofcapacitor C2 is to the maximum extent provided for the voltage controlcurrent source U1 output.

The value of capacitor C2 must be determined jointly according to acapacitor discharge voltage range and a required current and time of thepower amplifier. If the capacitor discharge voltage range is 9-6 V (i.eUstart=9; Ustop=6) and the power amplifier U1 output is 10 mA and 500milliseconds (mS), the U1 output energy is W, whereinW=(Iout)2*(R26+0.5)*t=10 mA2*(100+0.5)*500 mS=5.025 mJ. ThenC2>W*2/(Ustart2−Ustop2)=5.025 mJ*2/(81−36)=233.3 uF. It is very easy tofind electronic components conforming to the parameters above.

It must be explained that not all of the steps and modules in the flowsand structural diagrams above are necessary; certain steps or modulesmay be omitted according to actual requirements. The order in whichsteps are executed is not fixed, but may be adjusted as required. Thepartitioning of the modules is merely functional partitioning, employedfor the purpose of facilitating description; during actualimplementation, one module may be realized by multiple modules, and thefunctions of multiple modules may be realized by the same module; thesemodules may be located in the same device, or in different devices.

Hardware modules in the embodiments may be realized mechanically orelectronically. For example, one hardware module may comprise aspecially designed permanent circuit or logic device (such as adedicated processor, such as an FPGA or ASIC) for completing a specificoperation. The hardware module may also comprise a programmable logicdevice or circuit that is temporarily configured by software (e.g.comprising a general processor or another programmable processor) forexecuting a specific operation. The choice of whether to specificallyuse a mechanical method, or a dedicated permanent circuit, or atemporarily configured circuit (e.g. configured by software) to realizethe hardware module can be decided according to considerations of costand time.

The present invention has been displayed and explained in detail aboveby way of the accompanying drawings and preferred embodiments, but thepresent invention is not limited to these disclosed embodiments. Basedon the embodiments described above, those skilled in the art will knowthat further embodiments of the present invention, also falling withinthe scope of protection of the present invention, could be obtained bycombining code checking device(s) in different embodiments above.

The patent claims of the application are formulation proposals withoutprejudice for obtaining more extensive patent protection. The applicantreserves the right to claim even further combinations of featurespreviously disclosed only in the description and/or drawings.

References back that are used in dependent claims indicate the furtherembodiment of the subject matter of the main claim by way of thefeatures of the respective dependent claim; they should not beunderstood as dispensing with obtaining independent protection of thesubject matter for the combinations of features in the referred-backdependent claims. Furthermore, with regard to interpreting the claims,where a feature is concretized in more specific detail in a subordinateclaim, it should be assumed that such a restriction is not present inthe respective preceding claims.

Since the subject matter of the dependent claims in relation to theprior art on the priority date may form separate and independentinventions, the applicant reserves the right to make them the subjectmatter of independent claims or divisional declarations. They mayfurthermore also contain independent inventions which have aconfiguration that is independent of the subject matters of thepreceding dependent claims.

None of the elements recited in the claims are intended to be ameans-plus-function element within the meaning of 35 U.S.C. § 112(f)unless an element is expressly recited using the phrase “means for” or,in the case of a method claim, using the phrases “operation for” or“step for.”

Example embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A current sensor unit, comprising: arectification module, configured to convert an AC current to a pulsed DCcurrent; a power source conversion module containing an energy storageelement, connected to the rectification module and configured to storeenergy for the energy storage element based upon the pulsed DC currentduring operation in a charging mode and configured to generate a powersupply current based upon a voltage of the energy storage element; amode switching module, connected to the rectification module andconfigured to be bypassed by the power source conversion module duringoperation in the charging mode, and configured to bypass the powersource conversion module during operation in an energy release mode; acurrent sensor module, connected to the rectification module, the powersource conversion module and the mode switching module, separately, andconfigured to detect a pulsed DC current flowing back from the powersource conversion module or a pulsed DC current flowing back from themode switching module; a control module, configured to acquireelectrical energy from the power supply current, determine thatoperation is in the charging mode or the energy release mode based uponthe voltage of the energy storage element, and acquire a first detectionvalue provided by the current sensor module and relating to a pulsed DCcurrent; a self-calibration module, configured to generate a currentflowing through the current sensor module in a self-calibration process;wherein the current sensor module is further configured to detect thecurrent generated; and wherein the control module is further configuredto calibrate the first detection value based upon a second detectionvalue provided by the current sensor module and relating to the currentgenerated.
 2. The current sensor unit of claim 1, further comprising: asignal conditioning module, arranged between the current sensor moduleand the control module, and configured to acquire electrical energy fromthe power supply current and configured to condition the first detectionvalue and the second detection value.
 3. The current sensor unit ofclaim 1, wherein the control module is configured to determine thatoperation is in the energy release mode upon the voltage of the energystorage element being relatively greater than or equal to a first value,and determine that operation is in the charging mode upon the voltage ofthe energy storage element being relatively lower than or equal to asecond value, the first value being relatively greater than the secondvalue.
 4. The current sensor unit of claim 2, wherein the control moduleis configured to calculate a calibration factor based upon the seconddetection value and a theoretical value of the current generated, and isconfigured to calibrate the first detection value based upon thecalibration factor.
 5. The current sensor unit of claim 4, wherein thecontrol module is further configured to abandon a calibration factorrelatively greater than a first threshold or less than a secondthreshold, the first threshold being relatively greater than the secondthreshold.
 6. The current sensor unit of claim 1, wherein theself-calibration module comprises: a first switch; a diode, an anode ofthe diode being connected to the rectification module; a capacitor, afirst end of the capacitor being connected to a cathode of the diode; asecond switch, connected to a second end of the capacitor; a voltagecontrol current source, connected in parallel with the capacitor; and athird switch, arranged between the voltage control current source andthe current sensor module.
 7. The current sensor unit of claim 1,wherein the rectification module comprises a full-bridge rectificationcircuit or a half-bridge rectification circuit; and wherein therectification module further comprises: a transient voltage suppressionelement, connected in parallel with the full-bridge rectificationcircuit or half-bridge rectification circuit.
 8. A current detectioncircuit, comprising: a current transformer, containing a primary-sidecircuit and a secondary-side circuit; a current sensor unit, connectedto an output terminal of the secondary-side circuit, the current sensorunit including a rectification module, configured to convert an ACcurrent outputted by the secondary-side circuit, via the outputterminal, to a pulsed DC current; a power source conversion modulecontaining an energy storage element, connected to the rectificationmodule and configured to store energy for the energy storage elementbased upon the pulsed DC current during operation in a charging mode andconfigured to generate a power supply current based upon a voltage ofthe energy storage element; a mode switching module, connected to therectification module and configured to be bypassed by the power sourceconversion module during operation in the charging mode, and configuredto bypass the power source conversion module during operation in anenergy release mode; a current sensor module, connected to therectification module, the power source conversion module and the modeswitching module, separately, and configured to detect a pulsed DCcurrent flowing back from the power source conversion module or a pulsedDC current flowing back from the mode switching module; a controlmodule, configured to acquire electrical energy from a power supplycurrent, determine that operation is in the charging mode or the energyrelease mode based upon the voltage of the energy storage element, andacquire a first detection value provided by the current sensor moduleand relating to a pulsed DC current; a self-calibration module,configured to generate a current flowing through the current sensormodule in a self-calibration process; wherein the current sensor moduleis further configured to detect the current generated; and wherein thecontrol module is further configured to calibrate the first detectionvalue based upon a second detection value, provided by the currentsensor module and relating to the current generated.
 9. The currentdetection circuit of claim 8, wherein the self-calibration modulecomprises: a first switch; a diode, an anode of the diode beingconnected to the rectification module; a capacitor, a first end of thecapacitor being connected to a cathode of the diode; a second switch,connected to a second end of the capacitor; a voltage control currentsource, connected in parallel with the capacitor; and a third switch,arranged between the voltage control current source and the currentsensor module.
 10. The current detection circuit of claim 8, wherein thecontrol module is configured to calculate a calibration factor basedupon the second detection value and a theoretical value of the currentgenerated, and to calibrate the first detection value based upon thecalibration factor.
 11. The current sensor unit of claim 2, wherein therectification module comprises a full-bridge rectification circuit or ahalf-bridge rectification circuit; and wherein the rectification modulefurther comprises: a transient voltage suppression element, connected inparallel with the full-bridge rectification circuit or half-bridgerectification circuit.
 12. The current sensor unit of claim 3, whereinthe rectification module comprises a full-bridge rectification circuitor a half-bridge rectification circuit; and wherein the rectificationmodule further comprises: a transient voltage suppression element,connected in parallel with the full-bridge rectification circuit orhalf-bridge rectification circuit.
 13. The current sensor unit of claim4, wherein the rectification module comprises a full-bridgerectification circuit or a half-bridge rectification circuit; andwherein the rectification module further comprises: a transient voltagesuppression element, connected in parallel with the full-bridgerectification circuit or half-bridge rectification circuit.